Movement:
Lie flat on a Stability Ball and make sure your lower back is supported by resting it on the ball. Your legs must be at a 90 degree angle so it is important that you get the correct size ball.
With your arms beside your head, or in front of your body, crunch up by contracting the abdominal muscles (not a full sit up, crunch up so you are just lifting your shoulder blades off the floor).